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OZONE MICROSPARGING FOR RAPID MTBE REMOVAL ' William B Ke oot (K-V Associates, Inc , Mashpee, Massachusetts) ABSTRACT: Ozone nucrosparging allows rapid removal of methyl tert-butyl ether (MTBE)and benzene, toluene, methyl benzene, xylenes derivatives (BTEX) encountered at gasoline spill sites Bench-scale testing indicated applicability to MTBE removal Field testing was performed on two types of sites (1) a commercial automotive station which had suffered a gasoline sill, .and (2) a zone upgradient of a water supply well At the former, MTBE and BTEX compounds ' were treated, while at the latter only Nff`BE was present for treatment The objective at the station was remediation of soil and groundwater, whsle the second site objective was use of a "bubble fence" to control a plume advancing towards the well During a 20-day monitoring period at the station site, 95% reduction of BTEX and 99% reduction of MTBE was observed in a monitoring well within 18 ' ft (5 6 m) of the main injection well The protective bubble fence at the second site served to reduce exiting MTBE concentrations to non-detect levels ' INTRODUCTION MTBE presents a challenge for effective treatment in groundwater-based spills A common fuel additive in the United States since the 1990's, MTBE is resisianr io aerobic and anaerobic microuiai breakdown (Suflita and MorTnile, 1993) Activated carbon is not a very effective adsorber since MTBE is highly water soluble and poorly adsorbed (Reisinger, et al , 1986) Because of its ' relative low volatility, air stripping systems are capable of removing MTBE only if exceptionally high air to water ratios are used ' Ozone microsparging (the C-SpargeT"1 process)' appears capable of effecting rapid removal of MTBE from contarrunated groundwaters The use of microscopic bubbles with high surface-to-volume ratios allows efficient ' extraction of MTBE from aqueous to gas phase Differing from its attack on benzene ring compounds, ozone attack on ether occurs through insertion in the C- ' H bond The use of hydrogen peroxide supplementation does not appear necessary when microbubble ozone is used (Karpel vel Lehner, et al , 1994) The resultant breakdown products are normally tent-butyl formate, tert-butyl acetate, ' and tert-butyl alcohol These breakdown products are either further oxidized or biodegraded rapidly under the aerobic conditions promoted by ozone decomposition to oxygen ' TECHNOLOGY DESCRIPTION Ozone microsparging is a patented technology for in-Situ treatment of volatile organic compounds (VOCs) in groundwater and surface water The *U S Patent 95,855,775, other U S and foreign patents pending 1